At the present time, about 85% of clinical stage I patients who have a retroperitoneal lymph node dissection have an unnecessary operation because tumor is not found. Most of these patients have resultant sterility. Currently available and planned markers should permit accurate identification of those who will benefit from treatment. Further, modern chemotherapy of testis tumors is so successful that no harm will come to those who develop delayed evidence of residual or recurrent tumor. Based on these hypotheses, this study provides the first prospective randomized clinical trial to compare the efficacy of retroperitoneal lymphadenectomy versus no treatment of clinical Stage I non-seminomatous testis tumors after radical inguinal orchiectomy. The protocol design includes lymphangiography, ultrasound examination, computerized tomography of the abdomen, and measurement of serum and urinary tumor markers.